Pump for charging two-stroke internal-combustion engines



Jan. 16, 1951 F. R. LLOYD 2,538,463

PUMP FOR CHARGING TWOSTROKE INTERNAL COMBUSTION ENGINES Filed May 7, 1947 2 Shee ts-Sheet l 0 o o o o O"o o o 0-0 INVENTOR FREDERICK ROLAND LLOYD ATTORNEYS Jan. 16, 1951 F. R. LLOYD 2,533,463

PUMP FOR CHARGING TWOSTROKE INTERNAL COMBUSTION ENGINES F iled May 7, 1947 2 Sheets-Sheet 2 INVENTOR Q FREDERICK ROLAND LLOYD- B J MW ATTORNEYS Patented Jan. 16, 11951 PUMP FOR CHARGING TWO-STROKE INTERNAL-COMBUSTION ENGINES Frederick Roland Lloyd, Grimsby, England Application May 7,1947, Serial No. 746,441 In Great Britain July 24, 1944 Section 1, Public Law'690, August 8, 1946 Patent expires July 24, 1964 1 a Two stroke cycle internal combustion engines charged and/ or scavenged by crankcase action or by means of a separate pump are known but, gen- 2 Claims. ,(Cl. 103-157) erally speaking, they are inefficient unless valves be employed. The object of the present invention is-jan improved construction of pump whereby the maximum volumetric efiiciency may be obtained. .[To this end, and in accordance with the invention, there is employed a double-acting pump having a combined piston and sleeve valve havlng both reciprocatory and oscillatory movement in a cylinder, the piston being situated midway of the length of the sleeve valve and the cylinder being closed at its ends by inwardly projecting heads to provide a'close fit at the top and bottom of the piston stroke, one of the heads being apertured for the passage therethrough of a piston rod, wherein each half, upper and lower, of the sleeve valve is formed with two ports, an inlet and an outlet port, and the cylinder is formed with an inlet port midway of its height and with two angularly spaced outlet ports ofiset somewhat with respect to the mid-height of the cylinder.

..;;"'In the accompanying drawings one form of the invention is illustrated partly in section and partly in elevation, Figure 1 being a view as seen from the right, Figure 2, and Figure 2 being a view as seen from the left, Figure 1; while Figure 3 is a cross-section on the line 3-3, Figure 1.

As shown, a double-acting chargingpump for use with a twin-cylinder two-stroke internal com; bustion engine has a piston 11, with which is incorporated a cylindrical sleeve valve 1) mid-way of the length of which the piston a is situated; This combined piston and sleeve valve is slidable,

with combined reciprocatory and oscillatory movement in a cylinder closed at its ends by inwardly projecting heads d, e, to provide a close fit at thetop and bottom of the piston stroke, the head e being apertured, connected with a tubular extension j and fitted with a gas-tight bush g for the passage therethrough of a piston rod h. Each half, upper and lower, of the sleeve valve b is formed with an inlet port such as 7' and an'outlet port such as k at suitable heights and at suitable angles of displacement about its periphery. The cylinder 0 is formed with an inlet port m mid-way of its height and with two angularly spaced outlet ports n, n, offset somewhat with respect to the mid-height of the cylinder c, the one appertaining to the upper part a of the cylinder 0 being a little higher than the other which appertains to the lower part thereof.

The two outlet ports communicate with the two cylinders of the engine with which the pump operates.

Clamped to the piston rod h beneath the gastight bush g, and :within a continuation piece 0 of the tubular extension is a collar 10 carrying a radially extending pin q which projects into a ball 1" fitted in a spherical seating s eccentrically situated in needle rollerbearings t, in'a crank disc u on a lay shaft 1; mounted in suitable bearings" w, w, in a housing at secured to, andprojecting laterally from the continuation o of the tubular extension I and constituting therewith an oiltight casing. The .lay shaft 1; is driven by such as the internal combustion engine to be charged, at the same rate of rotation as the engine crankshaft. i

In use, and assuming the piston a to be at the top of itsstroke, the downward turning movement of the piston gives rise to negative pressure in the upper part of the cylinder 0 until the upper inlet port such as 7' of the sleeve b communicates with the inlet port m of the cylinder c whereupon a charge is drawn in to said upper part By the time the piston a reaches the bottom of its stroke communication between these ports 7' and m is cutoff and the charge is trapped; and as the piston a rises its oscillatory movement is in the opposite direction, the upperoutletnport such as Ic'of the sleeve valve b is brought into communication with the upper outlet port n of the cylinder 0 and the charge is expelled; Simultaneously the same action takes place beneath.

the piston (1 except that the charge is drawn in when the piston is. moving upwardly and, when it is moving'downwardly, the charge is expelled through the lower outlet port n of the cylinder 0,

it being understood that although the two outlet ports 71, n, of the cylinder 0 are not at the same When used with a single-cylinder internal combustion engine, the capacity of the cylinders of the pump should be at least equal to that of the cylinder of the engine and, if required, a supercharge of any desired value, within reason, may be obtained by increasing the diameter and/ or length of the pump cylinder 0.

If the piston rod h of the pump is to serve as a lubricant pump the lower end of the continua tion piece 0 of the tubular extension I in which the piston rod h is guided has a further continuation piece 2 which is arranged for connection as at I I, I2, Figures 2 and 3, with an unshown source of supply, such as the engine sump and with the lubricating conduits of the engine (not shown).

In the continuation piece 2 is a fixed sleeve [3 in which the end of the piston rod h slides and this sleeve I3 is formed with two longitudinally extending slots I4, 15 communicating with the connections II and I2 respectively,

The piston rod h is formed with longitudinally extending slots I6 and I! at 180 to one another. The lower end of the piston rod h is bored axially as at is and fits slidably over a plunger}!!! .prm jecting upwards axially into the continuation piece .2, and sleeve l3, being held in position by a cap 20 screwed on to said continuation piece a and clamping thereagainst a disc-shaped head 2'! on the plunger l9. As the piston rod h "reciprocates and oscillates, the slots 16, I1 come into communication, selectively with the slots M, :15 m the sleeve 1:3. ,As the piston rod it rises suction occurs in that part of its bore 18 above the plunger .IB and "when the slot in in the piston rod 71 communicates with the .slot 14 in the sleeve is leading from the source o'fssupnly, oil rushes and on th return (stroke this oil is forced out when the slot i 1 in the piston rod [h communicates with the slot 15 in the sleeve l3 leading to the lubricating conduits. It is desirable that :oil from the source of supply should flow by gravity to the pump.

taken of the maximum charging period of the engine. For instance the transfer ,port of the engine cylinder can be arranged to remain open after the exhaust port has closed, resultingin much heavier charge being admitted to the one gine cylinder and thereby increasing the volumetric eiiic'iency of the engine.

If the pump is to be used with a .singlemyiinder two-stroke internal combustion engine, both the outlet ports of the pump may be coupled with a.

common manifold communicating with the engine'cyl'inder, and if the swept volume oi the pump is the same as that of the engine cylinder,

the pump may be run at half the speed of the engine crankshaft.

The pump may be used with a four-cylinder two-stroke internal combustion engine having its four cranks set at '99" by arranging the pump to have a total swept volume equal to the total swept volume of two of the cylinders of the engine, so that two cylinders are fed from the upper outlet port 71, or the cylinder 1'; and two cylinders from the lower outlet port 11,, the pump being driven at engine speed. On each stroke of the pump, two cylinders oi the engine would be charged.

Where an engine has a greater number of cylinders, they may be arranged to be fed in groups from two or more pumps, e. .g., for "an eight-cylinder engine, two pumps could be arranged in the manner described above, each pump charging four cylinders.

I claim:

1. A double-acting pump for charging a twostrolre internal combustion engine, comprising a pump cylinder, :a combined piston and sleeve valve in a pump cylinder, a piston rod for the piston, means for imparting both reciprocatory and oscillatory movement to the combined piston and sleeve valve, the piston being situated midway of the length of the sleeve valve, and inwardly projecting heads on the cylinder closing the ends thereof and providing a close fit at the top and bottom of the piston stroke, one of said heads being apertured for the passage therethrough of the piston rod, each of the upper and lower halves of the sleeve valve being formed withtwo ports constituting an inlet and an outlet port and the cylinder being formed with an inlet port midway of its height and with two angularly spaced outlet ports offset with respect to the mid-height of the cylinders, 'a -lullricati-I-ig pump cylinder spaced from said first mentioned pump cylinders in which an end of the piston rod remote from said first mentioned piston is reciprocator'y, a fixed plunger projecting into the lubricating pump cylinder, the piston rod being formed with an axial bore to receive the fixed plunger and "with longitudinal slots, a source of lubricant supply, the lubricating pump cylinder being formed with longitudinal slots arranged for connection with the source of lubricant supply and with lubricating conduits in the in ternal combustion engine, the longitudinal slots in the piston rod being caused to communicate selectively with the longitudinal slots in the lubricating pump cylinder in order that the piston rod may serve as a lubricant pump.

2. A lubricating pump having a fixed cylinder,

a 're'ciprooatory and oscillatory piston rod, a fixed plunger projecting into the cylinder, the piston rod being formed with an axial bore to receive fixed plunger and being formed with longitudinalslots, a source of lubricant supply a lubricant delivery conduit, the cylinder being formed with longitudinal slots arranged for connection with the source of lubricant supply and the conduit, the longitudinal slots in the piston beinglcaused communicate selectively with the longitudinal slots in the cylinder, and means for imparting 'sbo'th reciprocatory and oscillatory movement to the piston'rc'd comprising a radially extending pin on the piston rod, a crank on adriven shaft, Ia ball-joint seating on the crank and a ball-joint seating, the radially extending pin projecting into said ball. V

FREDERICK ROLAND REFERENCES EITED The following references are of record in the file of this patent:

UNITED STATES PATENTS France Mar. 27., 1922 

